Sieve mail filtering recipes on the FastMail wiki, relevant to TuffMail.
Newspipe reads an OPML file and sends the feeds by email. It has one unique feature in that it can scrape the link url and send the full thing as a MIME attachment to an email. Good for feeds which only publish descriptions. Written in python.
rss2imap is a little like feed2imap but much, much older (last change in rss2imap was 2006 vs 2008 for feed2imap). rss2imap is written in perl and needs a few perl modules installed to work.
rss2email reads feeds and delivers them by smtp. Written in python by Aaron Swartz.
Feed2Imap reads feeds and posts them to an IMAP server, directly into the folder specified. Similar to rss2mail or rss2email but directly to an imap folder. Written in ruby included in Ubuntu repos.
Claws Mail is a lightweight mail client. The maemo port is specifically for Nokia tablets and supports advanced features way beyond the default mail client, such as imap folders, etc.